Photographic electrical copying device



April 17, 1951 A. G. THOMAS 2,549,546

PHOTOGRAPHIC ELECTRICAL COPYING DEVICE Filed Oct. 24, 1947 3 Sheets-Sheet l I I IIIIIIIIIII IO; 36 4e Lad)" 43 P HES-.2 44

April 17, 1951 A. G. THOMAS PHOTOGRAPHIC ELECTRICAL COPYING DEVICE 3 Sheets-Sheet 2 Filed Oct. 24, 1947 WWENTOR.

FIE. E

FIE-I51 '7 Patented Apr. 17, 1951 UNITED STATES PATENT OFFICE PHQTOGRAPHIC ELECTRICAL COPYING DEVICE This invention relates generally to devices for recording images and particularly to electronic copying or reproducing devices, including cameras. This application is related to my U. S. Patent No. 2,409,454.

An object is to provide a copying device in which reproductions of a letter, drawing, or lightand-shadow image of any kind are permanently made in or on a sheet of paper or other material by ionic bombardment.

Another obpect is to provide a camera in which pictures are made electronically, Without chemical baths or the like.

A further object is to provide an electronic reproducer or copying device in which electron images are passed through a thin metal element to aiTect a sheet of material adjacent the thin metal element. 7

Another object is to provide an electronic reproducer in which the image i formed by a scanning sequence.

An additional object is to provide special paper or film sensitive to electronic or ionic bombardment.

Other objects will appear in the specification.

In the drawings:

Figure 1 is a part sectional side elevation of an ionic type reproducer including a projector.

Figure 2 is a fragmentary front elevation, in part section, of a leak-proof roller drive for the device of Figure 1.

Figure 3 is a part sectional side elevation of an electronic camera, shown partly broken away.

Figure 4; is a schematic elevation of a lens and electronic system for use in electronic cameras or other reproducers.

Figure 5 is a part sectional side elevation of a scanning-type electronic reproducer employing a rotary drum and reels.

Figure 6 is a sectional side elevation of a perforated mask and associated evacuated element including a photosensitive surface and thin metal anode.

Figure 7 is a top plan view, in part section, of a scanning-type electronic reproducer employing movable parallel arms for holding the object to be copied and the paper to be imprinted or otherwise affected.

Figure 8 is a part sectional elevation of a novel drive for sealed containers, allowing objects Within the container to be moved in proportion to movement of a member outside the container.

In Figure 1, glass container I has plane transparent wall 2 and the remainder of the container can be covered with opaque material. Cover 3 is pivoted to the container by attached hinge 4 and top rubber gasket 5 is provided so that the cover may be held down by a suitable clamp (not shown) to seal the top edge against leakage of air or other gas. Two uprights 6 are joined by cross pieces l and have attached arms 8 serving as bearing supports for small rollers 9 over which ion-sensitive paper or sheet !0 is movable. This paper is rolled from reel I I to reel I2, the axle of which is supported in slots l3 in uprights 6, as bearings. The ends of the axle of reel I I may be held in depressions in spring clips I4 attached to uprights 6, so that the clips serve as bearings. The reels can be easily removed by lifting them. Uprights 6 may be set into the container or fastened.

Photoemissive cathode I8 of relatively fine mesh is suitably supported in the container and i is electrically connected with conductor I5 sealed in a Wall of the container and serving to connect the cathode to the negative terminal of battery or other voltage source I"! the positive terminal of which is conneced with apertured anode 15 which may be of relatively coarse mesh. Cathode I8 comprises relatively fine mesh wire screening and is coated with photosensitive material like caesium, silver-caesium combinations or the like, or copper oxide. The plane of cathode I8 is substantially parallel with the plane of wall 20 or wall 2.

Anode I5 is made of metal screening and is generally parallel and coextensive with cathode I8 and is suitably supported adjacent to cathode 88. Metal plate I9 may be fastened to wall 23 of the container to serve as an additional negatively charged plate to attract positively charged gas ions, if desired. This element I9 may be of metal screening and may have connected lead 2| sealed in the container.

Pipe 22 is sealed in the lower portion of wall 2 and provides a duct for removal of air from the container by means of connected evacuating pump 23. Valve 24 connected in the pipe line can be closed when desired, to maintain a more or less definite pressure of air or other gas in container I.

Container I is supported on base 26 which supports attached pedestal 25 on which cylindrical lens housing 21 is fastened. Similar smaller housing 28 can be telescoped into housing 21. These housings carry suitable lenses for focusing the image of letter or drawin 29 on cathode l8. Letter 2& is attached or supported on inclined door 38 which is pivoted to housing 2'! by hinge 3| and which is normally held in the position shown by spring catch 32 extending from frame 33 fastened to housing 2?. Reflector 34 having electric lamp bulb 35 is supported on frame 33 and directs light down against letter 29 when the lamp bulb is connected with a suitable source of current.

Paper H] which is rolled on reel H, is stretched across rollers S and is wound on reel [2 by manually turning crank or handle 36 shown in Figure 2. This handle is rotatable in bearing 31 fastened to container l and carries stron bar magnet 38. Similar magnet 39 is fastened to the adjacent end of the shaft of reel l2. Therefore, as magnet 38 is turned the magnet 39 is rotated with it and reel i2 is revolved to wind paper In around it. This construction prevents leakage.

Paper it may comprise an elongated sheet of any suitable material which is sensitive to ionic or electronic bombardment. It can be made in a variety of ways includin the following:

(a) Impregnate paper with iodide crystals, or iodide and starch so that the iodine liberated or sublimed under bombardment will produce a discoloration.

(2)) Provide paper with a colored layer and coat with thin metal, wax or other substance of low melting point. The wax or metal will be melted under ionic or electronic bombardment and will reveal the paper of different color.

(c) impregnate the paper with crystals of two colorless chemicals which produce a colored substance when combined. Another crystal substance containing water of crystallization can be included if water is necessary to the reaction. Bombardment will then produce acolored compound. The chemicals can be colored but will change color under bombardment. For instance, cupric bromide is brown in solution and produces a yellow precipitate of lead bromide when reacted with lead nitrate. Similarly litmus is blue in the presence of bases and pink with acids, and phenolphthalein is colorless in presence of acids and red or pink in presence of alkalies or the hydroxide ion. Likewise, methyl orange in acid solution is red and is yellow in alkaline solution. Congo red is blue with acids and is red with neutral or alkaline solutions.

Therefore if paper is impregnated with crystals of any of these substances in proper combinations, reactions can be avoided as long as the crystals are kept dry in some cases or separate in others. Each crystal or group of crystals can be coated by a plastic film of parafiin or any suitable substance and so reaction can be avoided until the bombarding electrons or ions puncture the coating or disintegrate the crystal. Then reaction will occur, producing a colored line or area. If water is essential to the reaction various substances containing water of crystallization can be used. Some of these are Glaubers salt, strontium chloride, cupric sulphate, barium chloride, Soda, calcium chloride, and the pentahydrate of cupric sulphate. The last named substance has a particularly low vapor tension and therefore will not tend to evaporate as much as Glaubers salt, for instance. These crystals containing water may likewise be coated with paraflin or other protective material. This coating can be applied by blowing the crystals through a parafiin vapor; after chilling the crystals to cause condensation of the vapor. Another method is to spray paraffin in carbon tetrachloride solution onto the crystals either before or after placin them in the paper.

It will be seen that bombardment will puncture the coatings or will liberate the various chemicals to cause combination, in the presence of water if that is included. As an illustration, if the paper I0 is impregnated with blue litmus and one of the previously mentioned sealed chlorides, electronic or ionic bombardment will liberate an acid water to turn the litmus red. Images can therefore be recorded. If permanent images are desired the paper can be unpregnated with starch and minute coated crystals of iodine and water crystals or water droplets can be distributed throughout the paper. Bombardment will then release the iodine to make permanent blue marks in the starch paper. Many other permanent compounds can be used in similar manner.

(d) The paper can be coated with diazo dye and parafiin globules containing ammonium carbonate or ammonia water can be distributed throughout the paper in similar manner a described in my co-pending application, Serial No. 752,584, filed June 5, 1947, now abandoned. When this composite paper is bombarded, ammonia is released and will react with the dye to form a permanent image.

(c) It has been demonstrated that electron bombardment causes certain carbon-containing substances to form carbon aggregates. It is possible therefore to use a clear plastic sheet or at least a colored sheet and to change its visible character by producing aggregations of carbon as a result of bombardment. Possibilities in this or similar connection are various commercial plastics, sugars, chlorophyll, carotene and the like.

(1) Small particles of ink can be contained in metal or plastic coverings or coatings and can be distributed throughout the body of a paper sheet. Bombardment will then puncture the coatings and will release the ink which will be absorbed by the paper to form. a line or other indication of the bombarding pattern.

(g) Some gems are changed in color by X-rays. Materials similarly changeable in color under electron or ionic bombardment can be used.

It is assumed that the photosensitive material of the cathode is chosen so that it will not b(. damaged by any gases or vapors given off by the paper.

In operation, cover 3 is clamped tight and battery I1 is connected in circuit with its negative pole leading to cathode I8- and its positive pole connected with anode I5. The paper NJ is assumed to be placed as shown with its sensitive side if any preferably facin cathode l8. Then valve 24 is opened and pump 23 is operated until a suitable degree of vacuum as indicated by an ionization gauge or other means is produced in container l. Valve 24 may then be closed and the pump stopped. Lamp 35 is then illuminated by closing a suitable switch, so that. an image of letter 29, which is previously placed on door 3?) before the door is snapped closed, is projected onto photosensitive cathode 18 through relative- 1y coarse mesh screen anode l5. The illuminated parts of cathode l8 will emit electrons which will be accelerated toward anode i 5 and will strike and ionize some of the gas particles remaining between the cathode and anode. The positive ions are accelerated through the interstices of cathode l8 and strike ion-sensitive paper l0 and produce a visible mark. Therefore the darkened areas of the cathode will produce few electrons and resulting ions; and the illuminated areas will produce relatively many, so that an image of letter 29 will be formed in paper ill. The ionic bombardment will be in proportion. to the degree of emissive cathode and element illumination of the cathode so that half tones can be reproduced or copied. If desired, plate L! can be charged to still lower negative potential with respect to cathode 18, in order to assist in pulling positive ions against or through the paper.

When lamp bulb is illuminated long enough for the ions to form an image, the lamp is extinguished and handle 36 is turned to bring a fresh section of paper into register with cathode l8. The exposed paper is wound on reel l2 and may be marked with cross lines to show various sections. When sufficient copies are made, lamp 35 being re-lighted for each copy, valve 24 is opened, cover 3 is unclamped and is raised and reel !2 is lifted out, the shaft ends passing through slots l3. Reel l I may likewise be lifted out.

The ions, being relatively heavy, exert a powerful bombarding action on the paper. A gas other than air can be admitted, if preferred, but in any case the working pressure in container I should be chosen for best results. The pressure should be so chosen that suflicient ions will be formed but the gas density should not be sufficient to cause excessive ionic collisions or scattering of the ions by colliding with gas molecules. Some of the ions will strike the cathode which should have a photosensitive surface sufficiently rugged to prevent serious damage. Various letters or drawings 7.9 can be placed in position for copying, without breaking the seal.

If it is desired to employ electron bombardment, plate l9 can be a semi-transparent photo- !8 can be the anode. A well known semi-transparent photoemissive' cathode comprises a very thin film of silver deposited on glass or other transparent material and a thin layer of caesium or similar material deposited on the silver. In this case the container I will be highly evacuated. As a modification paper as can be placed between element 58 and anode i5 and an image be projected through wall 26 onto cathode 58, plate if! being transparent or removed. The connections would be similar to those shown in Figure 4:.

In Figure 3, camera M! has lens system 4|, shutter actuator 42, and back .3 hinged at 44 to the other portion of the camera. and 46 are rotatable in suitable bearings as usual and spool is associated with an exterior key for winding so that paper lfia may be wound from spool 36 and onto spool 45. This paper may be similar to paper It described above.

Rectangular transparent glass box l! is fastened in the camera and has thin aluminum or other electron-permeable, gas tight metal sheet 48 suitably sealed to it in leak-proof manner to cover the rear opening 49 of the box. The inner front surface of the box is coated with semi-transparent caesium or caesium-on-silver photo-emissive layer 5!} and the box is preferably highly evacuated. A suitable inner supporting grid can be used to assist sheet 8 in opposing the outside air pressure. Layer 58 serves as the cathode and is electrically connected with the negative terminal of battery 5| fastened in the camera. This battery is connected in series with battery 52 through switch 53. The positive terminal of battery 52 is electrically connected with metal sheet 48 which serves as the anode.

In operation, paper We is started on spool 45 and presses against or closely adjacent to metal sheet 48. The camera is then focused upon an object and shutter actuator 42 is pressed, after closing switch 53. The image is focused upon cathode so that electrons are emitted from this cathode in proportion to the degree of illumi- Spools 45 place by a suitable spring clip.

nation thereof. Therefore an electron image, corresponding to the light image of the object focused upon, will be emitted from cathode 50 and will be accelerated toward positively charged anode 48 at high speed. If the potential difference between the cathode and anode is enough, the electron pattern will pass through the thin metal anode window 43 and will strike paper Illa to form in or on the paper a permanent reproduction of the image. This electron bombardment will continue as long as the shutter is open and switch 53 is closed. The switch is opened or the shutter closed when the picture is completed. When it is desired to make another picture or reproduction, the spool 45 is revolved by means of a suitable key until a fresh section of paper is in alignment with the window.

This construction has the advantage that the cathode is never exposed to outside atmosphere. This same principle can be used for making copies of drawings, letters and the like well as to photograph scenes or live objects. Back 13 and the camera housing can be of metal to confine the electrons. Batteries 5i and 52 can be removed through the back, after detaching element 51, or through special doors. G3 is held in It is obvious that the camera can employ the principles described in connection with Figure 1 as disclosed in my U. S. Patent No. 2,409,45l.

This camera can be used in airplanes to photograph terrain below as the plane travels. A mask with a slit, as shown in Figure 5, can be placed in front of the lens and the reel can be conr tinuously rotated at speeds proportional to speed of movement of the plane. The reel can be driven by a motor controlled by the plane speed. In this way a reproduction, copy, or picture of the terrain below will be made as the plane files along. This is particularly useful for military applications. The same principles can be applied to the type of electronic reproducer in which the reels are enclosed in the container.

Figure 4 illustrates means for reducing the area of the metal window. Lens Ea -l reduces the image so that small glass box 55 with a photosensitive cathode and sealed metal window 56 is used and is connected with battery 5? in similar manner as box M.

In Figure 5 back board 53 is fastened in vertical position to base 59 and carries fixed stub shafts 6!! and 5! on which reels 52 and 63 are rotatable. Suitable cotter pins or other means are provided to prevent the reels from slipping oh the shafts. Rollers and are supported on fixed shafts extending from board 58 and they support paper lllb which is rolled on reel 62 and which can be wound onto reel E53 by rotating pulley 6E fastened to this reel coaxially therewith. 1

Double pulley ill is attached to the outer end of roller 65 and a belt connects this pulley with pulley 66. Another belt connects pulley 67 with pulley 68 fastened to the outer end of sleeve 69 which is rotatable around shaft if! fixed to board 58. The inner end of the sleeve is fastened coaxially to circular end piece ll of transparent drum or cylinder '52 so that the drum is rotated when pulley 68 is revolved. Handle is is fastened to sleeve 69 on the outside ofpulley 68, and a cotter pin in shaft I0 is provided to prevent the sleeve from slipping off the shaft.

Elongated tubular electric lamp 14 is supported in a suitable socket on post 15 rising from base 59 and shown broken away. The axis of this lamp is substantially parallel with shaft 7G and opaque shield it supported on board '58 has a narrow elongated slit ll parallel with lamp 153 and coextensive therewith. Small rectangular glass box '18 (see also Fig. 6) has narrow elongated photo-emissive semi-transparent cathsurface l9 parallel with slit ll and coelxtensive therewith. The box is provided with opening 35* over which thin metal sheet Si is sealed to glass box 58. This metal sheet or strip is narrow and is parallel with cathode surface l9 and is approximately as long as this surface. The cathode is electrically connected with the negative terminal of battery 82 through switch 83. The positive terminal of the battery is connected with strip at. Box 78 extends from board 58 and is supported from this board in any suitable manner. Apertured anode 31a may be included. and can be charged positively, if desired. In that case element 8! need not be electrically connected.

In operation, letter or drawing 84 is wrapped around transparent drum l2 and is held in place by adhesive tape or clamps. Handle i3 is turned until one edge of the letter is adjacent slit 1?. Then lamp M. is energ ed by connecting it in asuitable circuit and switch is closed. Then handle '53 is turned to sweep the letter past slit Ti. As the letter passes, the belts rotate roller to feed paper synchronously past metal electron window 85 and to wind the exposed paper on reel 33. The light from lamp is is therefore modulated by typing or other markings on the letter so that the cathode strip 39 will emit a line of electrons of proportional modulated dens" y. This line of electrons will be accelerated to pass through thin metal window 8! to strike electron-sensitive paper it?) closely adjacent the window. The moving paper is therefore scanned by a varying line of electrons passing through win-" ow all to strike it. When drum i2 is rotated un l the end of the letter is reached, the electronproduced image is therefore already formed in paper 5%. A succession of copies can be made by continuing to rotate handle '53. Switch 83 can be automatically or manually opened between copies, if ti ired, as may be a switch controlling current to lp Ihe exposed paper can be removed from reel 53 when the desired copies are produced. A suitable light-proof housing can be placed around box 78 or the whole mechanism, if preferred.

In Figure '7, bearing block 35 rises from attached base 86 and has two parallel horizontal slots through w ich integral parallel arms 8'! and 88 are slidable. Arm 87 carries glass or other transparent plate 8? the top edge of which is shot *1. Similarly, arm 83 carries plate 58 to which electron-sensitive paper sheet We is attached. Glass box it is as described in connection with Figure 5 except that in this case cathode strip '5 is aligned to be perpendicular to base In either drawing the glass box '18 may be opaque except for a narrow strip in alignment with cathode strip i8 and slit I? in opaque shield fastened to base 88. Lamp 14 and slit 11 are likewise perpendicularly positioned. Letter is attached to glass plate 89.

In operation, the lamp is illuminated after placing letter and the cathode and anode of box it are connected to a source of potential as shown in Figure 6. Then arms il -38 are pushed through block 85 to cause the li ht beam passing through slit ll to scan the letter. thus producing a scanning line of electrons to strike paper [90 in manner described in connection with Figure 5.

Figure 8 shows means for mechanically rotating a member through a sealed wall. Equivalent parts are numbered as in Figure 2. Disc 9! is fastened to the end of shaft 82 integral with handle 36 having rotary bearing in bracket 3?. The disc has a hemispherical depression in its face in which the rounded end of arm 93 is fitted. This arm is welded, clamped, or otherwise fastened in an opening in flexible diaphragm 94 sealed in container i to close opening 95. Arm 93 is sealed to diaphragm fi l in leak-proof manner. The inner extension 96 of the arm also has a rounded end which is slidably fitted into a hemispherical depression in disc 9? fastened coaxially to the shaft of reel [2.

In operation, handle 36 is turned which causes arm to be swept around in circular paths on both sides of the diaphragm which flexes to allow the 'rcular movement even though the arm is rigidly sealed to the diaphragm at the periphery of the opening. Therefore circular movement of a member in a sealed container can be achieved in this manner without danger of leakage. This can be used for many purposes, in connection with electronic tubes, electron microscopes, and for other uses. It is not necessary that the exact movement shown be used as arm 93-46 can be swung through an arc to manipulate members, or an associated rack and pinion can be employed.

Numerious details can be changed and modifications made without departing from the broad principles of the invention. For instance, the can be arranged in stacks of sheets so that a plurality of copies will be made simultaneously. Likewise, the sheets may be placed between the cathode and anode or adjacent thereto, one by one, automatically. Other variations are easily possible.

What I claim is:

1. In an image reproducing device, a substantially evacuated container having a light-transmitting portion, an element in said container adapted to receive light from said portion and emitting electrons where struck by said light, said container being of material relatively impervious to passage therethrough of gas ions or molecules and having an opening through which electrons from said electron-emitting element are adapted to pass, and an electron-permeable element sealing said opening against passage of gas molecules and gas ions.

2. In an image reproducing device, a substantially evacuated container having a light-transmitting portion, an element in said container adapted to receive li ht from said portion and emitting electrons where struck by said light, said container being of material relatively impervious to passage therethrough of gas ions or molecules and having an opening through which electrons from said electron-emitting element are adapted to pass, an electron-permeable element sealing said opening against passage of gas molecules and gas ions, and means for directing light to said light-transmitting portion.

3. In an image reproducing device, a substantially evacuated container having a light-transmitting portion, an element in said container adapted to receive light from said portion and emitting electrons where struck by said light, said container being of material relatively impervious to passage therethrough of gas ions or molecules and having an opening through which electrons from said electron-emitting element are adapted to pass, an electron-permeable element sealing said opening against passage of gas molecules and I gas ions, mean for directing light to said lighttransmitting portion, and means for producing an electrical field to accelerate said electrons.

4; The device of claim 1, said electron-emitting element being relatively long and narrow.

5. The device of claim 1, said light-transmitting portion being relatively long and narrow.

6. The device of claim 1, said light-transmitting portion and said electron-emitting element being relatively long and narrow and substantially parallel.

7. The device of claim 2, the efiective area of said electron-permeable element being relatively long and narrow.

8. The device of claim 2, said electron-emitting element and said electron-permeable element being relatively long and narrow and substantially parallel.

9. The device of claim 1, said container having a pair of parallel walls, said light-transmitting portion being in one said wall and said opening being in the other said wall.

10. The device of claim 1, and including means for producing a light image of an object to be reproduced. I

11. The device of claim 2, said means for directing light including a lens to form a light image of an object to be reproduced.

12. The device of claim 2, and including means for causin relative movement between said electron-permeable element and electron-sensitive material adjacent thereto.

10 13. The device of claim 3, and including means for causing relative movement between said electron-permeable element and electron-sensitive material adjacent thereto.

ALBERT G. THOMAS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,148,227 Heeley July 27, 1915 1,378,118 Jacobsen et a1 May 17, 1921 2,116,901 Knoll May 10, 1938 2,153,628 Knoll Apr. '11, 1939 2,234,717 Altman et a1 Mar. 11, 1941 2,281,638 Sukumlyn May 5, 1942 2,297,691 Carlson Oct. 6, 1942 2,357,674 McConnell et a1. Sept. .5, 1944 2,357,809 Carlson Sept. 12, 1944 2,409,454 Thomas Oct. 15, 1946 FOREIGN PATENTS Number Country Date 188,030 Great Britain Oct. 23, 1922 326,200 Great Britain Mar. 5, 1930 375,639 Great Britain June 30, 1932 391,100 Great Britain Pub. 1933 464,112 Great Britain Apr. 12, 1937 

